The IDNR contracted Lawson-Fisher Associates to conduct a hydrologic/hydraulic study of the Hamilton Lake Dam System, design and construction phase services relating to Dam improvements.

Using the results from the hydrologic/hydraulic analysis, Lawson-Fisher Associates was able to justify the use of a design flow that was significantly less than initially required. This was due to the impact, shown on the HEC-RAS model, that the tailwater has on the discharge from the spillway. The Final design included overtopping protection, energy dissipation, toe drain improvements, and replacement of an existing culvert crossing SR 1/SR 427 with an arch structure.